A femto base station is basically a low cost and low power base station (BS) transceiver, which is installed indoors (e.g., in a home or office). A femto base station is usually connected to the Internet via cable, a digital subscriber line (DSL), an on-premise fiber optic link, or a similar Internet Protocol (IP) backhaul technology. This connection is used to integrate the femto base station with a wireless operator's core network.
A femto base station serves a geographic area known as a femto cell over a single carrier or channel. A femto cell typically covers a smaller geographic area or subscriber constituency than a conventional macro cell. For example, a femto base station typically provides radio coverage in a geographical area such as a building or home, whereas a conventional macro base station provides radio coverage in a larger area such as an entire city or town. Femto cells may exist within or overlap macro cells.
The function of a femto cell is similar to that of a Wireless Local Area Network (LAN), and provides operators a relatively low cost solution for extending coverage areas and off-loading users from the cellular network.
In conventional wireless femto base station deployments in multiple technologies such as WiMAX, long term evolution (LTE), enhanced-voice-data-only (EVDO), etc., a relatively large number (e.g., 100 s) of femto base stations co-exist with macro base stations. But, conventional handoff methods based on neighbor base station scanning typically performed by mobile stations are designed for a limited set of neighbor macro base stations. Thus, these conventional methods are not adequate for scenarios having to deal with larger numbers of femto base stations in addition to the conventional macro base stations at least because: (1) conventional scanning of all the potential target base stations drain the device battery; (2) limited space in the air interface within the broadcast messages restricts inclusion of all the potential base station details; and (3) relatively long scanning periods of all the potential target base stations affect data transmission/reception.
Moreover, the presence of larger numbers of neighbor base stations (e.g., macro and/or femto) also impedes efficient management of these neighbors for potential handoff because reporting too many base stations to the mobile station in an advertisement field is impractical.